Field of the Invention
The present invention relates to a process and apparatus to make shaped confectionery products from a chocolate or other material which approximates a behavior similar to a Bingham material. More particularly the present invention relates to the formation of such shaped confectionery product by a cold extrusion process.
Confectionery products such as chocolate products are typically made from a molten mass of chocolate after the chocolate has been formulated. There are many different chocolate formulations such as dark and light chocolate, milk chocolate and white compound coatings which typically include sugars or sugar substitutes, dry milk powders, emulsifiers, and a fat such as cocoa butter or vegetable or other fat substitutes.
Traditional chocolate processing to make shaped chocolate products, i.e., bars or other shapes, and enrobed products are carried out while the chocolate is in a molten or flowable state. Following a melt conditioning process, known as tempering, usually at a temperature of between 27xc2x0-32xc2x0 C., the chocolate is molded into a desired shape by molds or formed into a desired shape by other molding processes while the chocolate is still in a molten state at an elevated temperature above ambient temperature.
Recently there has been reported work on the formulation of chocolate products by a cold extrusion process, e.g., Becket et al., The Cold Extrusion of Chocolate, Transcript of the Institution of Chemical Engineers, Vol. 72, Part C, March 1994, pp. 47-54, U.S. Pat. No. 5,439,695 and European Patent Application EP 0 730 827, published Sep. 11, 1996. The processes and apparatus disclosed in these publications do not teach or suggest use of a cold extrusion process to make chocolate products having a distinct shape such as a lentil shape, star shape or a shaped figure to represent seasonal holidays such as Easter, Halloween, Christmas or any other shaped figure. The extrusion processes and apparatus disclosed in these prior publications utilize molding techniques and apparatus which by their nature preclude the formation of precisely shaped chocolate products.
European patent EP-0-776-608 discloses a process for molding chocolate products in a non melted state. This process involves subjecting crystallized chocolate to die extrusion to form a malleable sheet. This sheet is then fed directly into forming rolls. This patent does not disclose or suggest a process involving forming a particulate feedstock or the unique products formed by shape particulate Bingham plastics. The patent also does not disclose or suggest a process for generating release of the formed sheet from the rolls by controlled differential motion between the rolls.
Devices for roll compacting or sintering shaped articles by passing granular material between counter-rotating rolls having spaced depressions in the rolls have been utilized heretofore for many types of products. Merely illustrative of some of these prior art devices are U.S. Pat. No. 5,358,727 which discloses counter-rotating rolls with mold cavities to form food products from fruit such as pitted prunes or berries; U.S. Pat. No. 4,411,611 discloses counter rotating rolls to form briquettes from pulverized and/or granular material; U.S. Pat. No. 5,073,323 which discloses an apparatus for compacting non-extrudable ceramic tumbling media between counter-rotating form rolls; U.S. Pat. No. 4,017,241 which discloses a briquetting apparatus for forming briquettes of metallic ore; and U.S. Pat. No. 3,255,285 which discloses counter-rotating ridged rolls to compact granular fertilizers and animal feed.
Additional prior art to compact and form briquettes using various types of presses to compact the material are shown in U.S. Pat. Nos. 5,667,824, 4,882,105, 4,394,395 and 4,178,392.
None of these prior art devices and processes suggest use of counter-rotating rolls to compact a material having a Bingham plastic rheology and none of these prior art devices disclose or suggest using a differential movement between the counter-rotating rolls to assist in release of the sheet of formed pieces and interconnecting web from the rolls.
Currently in the manufacture of a shaped chocolate product, for example, a lentil shape which is subsequently provided with a sugar coated shell, the chocolate mass in molten form is provided to relatively large diameter counter-rotating rolls which have an appropriate lentil shaped depression in the face of each roll. Side panels are provided to keep the molten chocolate confined to the area between the rolls and the molten chocolate sits in a puddle above the rolls. As the rolls turn the molten chocolate is drawn into the nip between the rolls and shaped to the appropriate lentil shape by the mating indentations in each roll.
The rolls are chilled by flowing a cooled liquid such as 50/50 by volume an ethylene glycol and water solution at approximately xe2x88x9220xc2x0 C. through the rolls beneath the chocolate contact surface to draw heat from the molten chocolate to allow it to be formed to shape with a sufficient degree of rigidity to retain the imparted shape. The formed chocolate exiting from the rolls is what may be termed in a semi-solid state requiring additional cooling to bring the chocolate to room temperature where it can be readily processed to remove the flashing between each lentil and then subsequently sugar coated, or for baking chocolate pieces just deflashed and packaged. This process also requires dehumidification near the form rolls to withdraw moist air.
The additional cooling step after passage from the formation rolls requires the use of cooling tunnels, conveyors and additional refrigeration to provide a proper cooling temperature within the cooling tunnels.
Because the process begins with chocolate in a molten state which must flow into the shaped depressions, of necessity, larger sized shapes must be employed and, smaller shapes, or shapes having irregular variations such as star shapes or shaped figures are difficult to provide with this traditional method and apparatus because of the flow properties of molten chocolate when it contacts a chilled surface.
In addition, the diameter of the rolls must be relatively large and the rolls turn at a relatively slow speed to insure that the molten plastic is drawn from the puddle of chocolate between the roll nips to fill all of the formed space in the opposed rolls.
These current processes require relatively large equipment size, use of refrigerated fluids such as an ethylene glycol solution to chill the formation rolls, dehumidification and use of cooling tunnels with added refrigeration which all add to the manufacturing cost and complexity.
Accordingly, there has been a need in the confectionery field to provide a process and apparatus to more economically form shaped confectionery products, such as chocolate, and increase throughput by the ability to operate formation equipment at higher throughput rates at less cost due to the elimination of the use of super cooled coolants and refrigeration equipment in cooling tunnels.
In a preferred embodiment of the present invention applicable to the forming of shaped confectionery products, a preferred confectionery product being chocolate, a pair of opposed rolls are provided having the desired shape for the formed chocolate product as a depression on the surface of each roll. The rolls are mounted for counter rotation with no or a slight space between the rolls and a hopper is provided above the counter-rotating rolls to direct, by a gravity feed, highly crystalline tempered chocolate in the form of flakes, shavings or granules to the rolls. Because the Bingham plastic material used in this process is mostly crystallized and cooled before forming, it allows for the use of more efficient cooling and crystallization methods to arrive at the desired final product morphology, temperature and crystallization state. There are many cooling and/or crystallization processes involving mechanical agitation and manipulation of Bingham plastics which can be used on the feed stream of the process of the present invention to arrive at the desired morphology, temperature and crystallization state. These more efficient processes often cannot be used for hot formed products because they are crystallized and cooled after forming which would result in mechanical damage to the desired final piece shape.
The counter-rotating rolls draw the chocolate pieces down between the nip of the rolls to compress and compact the chocolate pieces in a process akin to sintering to form the chocolate into the desired shape. The chocolate leaves the rolls in a downward direction in sheet form with the formed chocolate pieces interconnected by a thin web of chocolate. The bulk temperature of the chocolate is not changed. A small portion of the chocolate, specifically that in what is called the Beta 3 form and below melts. However, this melting is not significant and no additional cooling in cooling tunnels is necessary.
The sheet is then deflashed and the chocolate pieces agitated in a conventional manner to smooth the edge where the web interconnected the formed pieces. The chocolate pieces may then be further processed, if desired, by coating with a sugar shell or packaged without coating for ultimate consumer use.